This invention relates to the cleaning of disks containing encoded information, such as phonorecords and videodiscs, and more particularly to cleaning such disks with a roller having an electrostatically activatable, mechanically chargeable outer surface.
Dust particles (i.e., foreign matter) on the surface of a phonorecord can interfere with the fidelity with which the sound, i.e., the information encoded on the phonorecord, is reproduced when the phonorecord is played. The annoying and disruptive transients, popping and crackling resulting from the dust particles are well known. Substantially the same problem occur with dust particles on videodiscs, namely the pictures and the sound may be distorted during playback because of the presence of dust particles.
Various systems to deal with the problem of cleaning dust particles off phonorecords have been proposed. Among them are those systems shown in the following U.S. patents: No. 2,322,986 to Weiss et al.; No. 2,977,127 to Mertes; No. 3,958,292 to Powell; and No. 3,965,520 to Maier.
The patent to Weiss et al. discloses a thread removing and disk cleaning mechanism having a cleaning roller 27 in the form of a frustum of a cone. The roller, according to the patent, is provided with a surface 32 of mohair cloth, felt, silk, soft cotton, or any other suitable material, preferably electrically non-conducting, capable of holding particles of wax or resin, dust, and the like, either solely by mechanical action or by electrostatic action or both. The patent expresses a preference for a surface for the roller which has the capacity for causing the threads, chips and other particles resulting from the initial cutting of the record to adhere thereto by mechanical action; even though, according to the patent, the static electricity generated by the cutting of the record may be sufficient of itself to cause adherence to the roller. The roller itself is stated to be made of wood, molded resin or other plastic parts, and the like, or of light metal.
The patent to Mertes shows a device for cleaning phonorecords having two arms 1 and 2 covered with a pad 6 of resilient synthetic resin foam (preferably polyurethane foam). According to the patent, the foam pad "wipes out" electrostatic charges on the phonorecord being cleaned. Preferably (see col. 1, 11. 62-66) pad 6 is impregnated with a liquid to increase the cleaning effect.
The Powell patent describes a roller covered with adhesive tape for cleaning phonorecords, the bond strength between the adhesive particles extending that between the adhesive particles and the record face so that adhesive particles do not separate from the tape and become attached to the record. To clean a record, the roller with fresh adhesive tape exposed is rolled across the surface to be cleaned before the phonorecord is played. The patent to Maier shows a similar cleaning system except that in the case of the Maier patent the cleaning device is not an adhesive coated roller but rather is a special brush dampened with an anti-microbial liquid cleaning composition.
Applicant is also aware of another phonorecord cleaning apparatus sold by Musonic Ltd. of St. Albans, England under the trade designation Colton Electroduster. This apparatus includes an arm, supported by a pillar at the edge of the turntable, which terminates in a rubber rimmed wheel resting upon the label of a phonorecord to be cleaned. According to a review article on the apparatus, the wheel rotates as the record is played to cause an electrostatic belt of soft fibers to traverse the record surface radially. According to the article, the belt is charged during play of the record by passage over a cleaning pad, which pad also collects any loose debris attracted by the belt. Simultaneously, a velvet tracking pad laterally traverses the disk before the stylus to clean the grooves of the phonorecord while the record is being played.
The devices mentioned individually suffer from several disadvantages, among them being undue complexity, the need for or desirability of a cleaning or antistatic fluid, less than optimal cleaning of the phonorecord, and expense of the systems themselves.